This application relates to U.S. patent application Ser. No. to be assigned based on Japanese Patent Application No. 11-343385 filed Dec. 2, 1999 entitled xe2x80x9cMeasuring Apparatus and Layer Forming Processing Methodxe2x80x9d by t. Ohtsubo et al., the disclosure of which is incorporated herein by reference.
The present invention relates to an apparatus for monitoring a state of an inner wall surface of a processing chamber in layer forming and processing operation such as processing of forming thin film, etching processing of forming minute patterns on thin film or the like in the fabrication of devices such as semiconductor devices and liquid crystal devices having combined minute thin film patterns and a method of forming and processing a layer by means of a layer forming and processing apparatus incorporated with the monitoring apparatus.
In the layer forming processing and the minute pattern forming processing used in the fabrication of semiconductor devices or liquid crystal devices, a deposited layer is formed on an inner wall surface of a processing chamber during the processing. When a thickness of the deposited layer is increased, dust is produced by exfoliation of the deposited layer and it is difficult to attain the layer forming processing with high accuracy.
As a method of monitoring a layer deposited on the inner wall surface of the processing chamber, for example, JP-A-9-36102 and JP-A-11-140655 disclose a method of irradiating the inside of the processing chamber with measurement light from one window formed in the processing chamber and measuring the measurement light emitted from the other window formed in the processing chamber to monitor a state of the deposited layer on the basis of variation of the measurement light.
However, even when the deposited layer is not thick, there is a possibility that the deposited layer is peeled off if a state of irregularities of a surface of the deposited layer is remarkable. Accordingly, if not only a thickness of the deposited layer but also the state of the surface can be detected, it can be exactly judged whether cleaning of the inner wall surface of the processing chamber is required or not.
However, in a measuring method of the deposited layer disclosed in the above documents, the measurement light passing through the windows formed in the processing chamber is influenced by both of a thickness of the layer deposited on the windows and scattering of the measurement light due to irregularities formed in the surface of the deposited layer and both of them cannot be detected separately. Accordingly, the state of the deposited layer in the processing chamber cannot be monitored with high accuracy.
It is a first object of the present invention to provide a monitoring apparatus capable of monitoring a thickness of a deposited layer formed on an inner wall surface of a processing chamber and a state of a surface of the deposited layer separately.
It is a second object of the present invention to provide a dry processing method and a dry processing apparatus for monitoring a thickness of a deposited layer formed on an inner wall surface of a processing chamber and a state of a surface of the deposited layer separately and cleaning the inner wall surface of the processing chamber at a proper time before dust is produced in the processing chamber. The present invention is to solve at least one of the above objects.
In order to achieve the above object, according to an aspect of the present invention, a monitoring apparatus for detecting a thickness of a layer deposited on an inner wall surface of a processing chamber of a dry processing apparatus, comprises a measurement window formed in the inner wall surface of the processing chamber and which can transmit light, a device for irradiating the measurement window with measurement light at an incident angle that the measurement light is totally reflected by an inner surface of the measurement window on the side of the inner wall surface of the processing chamber, a detection device for focusing the measurement light reflected by the inner surface of the measurement window and a surface of the layer deposited on the inner surface of the measurement window to detect the measurement light, and a device for evaluating the layer deposited on the inner surface of the measurement window on the basis of a detection result of the detection device.
In the above aspect of the present invention, a reflection portion which reflects the measurement light and a transmission portion which transmits the measurement light are formed on the inner surface of the measurement window on the side of the inner wall surface of the processing chamber, and the evaluation device evaluates the deposited layer on the inner surface on the basis of the measurement light reflected by the reflection portion formed on the inner surface and the measurement light which the transmission portion transmits and is reflected by the surface of the layer deposited on the inner surface. Alternatively, a reflection and transmission layer which reflects part of the measurement light and which transmits the remaining part of the measurement light is formed on the inner surface of the measurement window on the side of the inner wall surface of the processing chamber, and the evaluation device evaluates the deposited layer on the inner surface on the basis of the measurement light reflected by the reflection and transmission layer formed on the inner surface and the measurement light which the reflection and transmission layer transmits and is reflected by the surface of the layer deposited on the inner surface.
In order to achieve the above object, according to another aspect of the present invention, a dry processing method of generating discharge in a processing chamber in a predetermined gas atmosphere to process an object to be processed so that a deposit produced in the processing chamber is cleaned, comprises irradiating a measurement window, which is formed in an inner wall surface of the processing chamber and can transmit light, with measurement light at an incident angle that the measurement light is totally reflected by an inner surface of the measurement window, focussing the measurement light reflected by the inner surface of the measurement window and a surface of a layer deposited on the inner surface to detect the measurement light, evaluating the layer deposited on the inner surface of the measurement window on the basis of the detected and reflected light of the measurement light, and deciding a time of cleaning the deposit produced in the processing chamber on the basis of the evaluation of the deposited layer.
In order to achieve the above object, according to still another aspect of the present invention, a dry processing apparatus for generating discharge in a processing chamber in a predetermined gas atmosphere to process an object to be processed so that a deposit produced in the processing chamber is cleaned, comprises a measurement window which is formed in an inner wall surface of the processing chamber and can transmit light, a device for irradiating the measurement window with measurement light at an incident angle that the measurement light is totally reflected by an inner surface of the measurement window on the side of an inner wall surface of the processing chamber, a detection device for focusing the measurement light reflected by the inner surface of the measurement window and a surface of a layer deposited on the inner surface to detect the measurement light, and a device for evaluating the layer deposited on the inner surface of the measurement window on the basis of the detection result of the detection device and deciding a time of cleaning the deposit produced in the processing chamber on the basis of the evaluation of the deposited layer.
In the above aspect of the present invention, a reflection portion which reflects the measurement light and a transmission portion which transmits the measurement light are formed on the inner surface of the measurement window on the side of the inner wall surface of the processing chamber, and the evaluation device calculates a thickness of the deposited layer on the inner surface on the basis of a deviation between an optical axis of the measurement light reflected by the reflection portion formed on the inner surface and an optical axis of the measurement light which the transmission portion transmits and which is reflected by the surface of the layer deposited on the inner surface and judges a state of irregularities of the surface of the deposited layer on the basis of the calculated thickness and a quantity of the measurement light reflected by the reflection portion.